Apparatus for forming columns in situ



Oct. 23, 1934. o. STERN APPARATUS FOR FORMING COLUMNS IN SITU Filed Aug. 8, 1932 3 Sheets-Sheet 1 uvenrToR Oct. 23, 1934. "o. STERN APPARATUS FOR FORMING COLUMNS IN SITU Filed Aug. 8, 1932 3 Sheets-Sheet 2 Oct. 23, 1934. o. STERN 1,978,332

APPARATUS FOR FORMING COLUMNS IN SITU Filed Aug. 8, 1932 3 Sheets-Sheet 3 MVVGNTMZ Patented Oct. 23, 1934 PATENT orrioe nrm gA'rus roe Font/[mo COLUMNS n, H SITU. H

Ottokar Stern, Vienna, Austria, assignor to Stern-Gesellschaft "fiir moderne Grundbau technik m. b. H., Vienna, Austria, a company of Austria Application August 8,1932, Serial No. 627,983

Austria September 5, 1331 5 Claims. (01 s n-5 1 this .iereeti n relates to an a a a s for h prediction in ste l? o um s o h ois ol e fied materials in the ground andm'ore particularly relate s to the production of concrete piles. The 9ilF" Q1? ?iP 5 t md t q V ueew 1?? ee unname materiel terse W ll lumee of e' 1 91 he It? Feli es ma he 9? an len th a an det r- "th ma be 9 un io m d a w eter or tvith widened (bulbous) portions at the tom o inte m di e Portion A e amp o porous lumn 'ie wtic th I?- e rlies th re ma nti ned: the

rub l filters in W er suppl insta ett H more .ticu erl ro r e r s Where the withdrawal instead o being .efie e o o e wells isiv th a vantag e ecte om sha ts dr ven to th ground whi h re fill d w th en o rubble; th dtaillege ha t e i l lt l' so draina nsyst ms. n which? b m an o ubblefil edideepshatts, the dr ina of a ge xons .q ll be fiected. :by, heir ve t al onne i nw h e xere t d a a s il (low r l v l it? m e e fe tive y than byanetw rk o ditch s an se ial th impr v ment o bu l Q by mean 9 made situ t m d p which 0 grave o withqu e bin in a nt which. W produced hy other m ans mos not nly e t an xpenditur o muc t m and s cost but are also more or less u re iehl in q e i tiqn- -'lhe intent; -mns it in a a pa tu r e produ t o s u o col ns in h round which tmc ue tim red .3 Pl nge em i d F9 int ra s nid md an -iQl ewer We? fet as m thzsaid plung r en ade t #9 mi ill nre ii h ott a ow-inter a th nse d il mlge i d i aloiil s idln meteo Jes ti ht y W thi e-"Fi b The present nve t on i in li tul y s r bed below with reference to the accompanying drawo rhic i ustre e ex m les 1 W t m ntio ma b :Wlflfid i t f e t orln' h'se drawin s:- l r 1 Eie esl and show in sect nal elevation two diff ren enstmc i n th ep z r u a c rd- :in to th .inrentiq i e 2 en s are g os a tiqns taken 9 41 l ne $1111; of i u 1 en i lYm Y o i ure 3 espec el i ur 1 t0 illustrate variousstag es of the rnethod" of buildg iles withanapparatus according to empreseetihveetienit; c suis -itd Q new i o sa e w'e and ending in headed portions at their top ends. At both sides the plunger 3 is provided with jaws 9 (Fi 2) or the like provided with vertical bores through which extend the guide-rods 5, so that the plunger 3 can be lifted forthe'leng'th of the so guide-rods 5 Without taking with itthe follower fl. The latter is raised during the upward stroke of the plunger 3 only when the jaws 9 co -onerate with theheaded portions of both guide-frodjs 5'.

The raised position of plunger and follower is 5 indicated in dotted lines; Now if in this positionconcrete is poured into the funnel located at the top end of the tube 1, the concrete drops down the space 7 and through the bore 6 of the foll'oyver {1 (which now is uncovered by the plunger '3) into 7; the bottom space 8 ofthe tube, this operation being facilitated considerably by the upward movement of the parts 2, 3 and 4'.

During the downward movement of the rod 2 first the annular follower f1: settles down on the Z5 concrete charge in the compression chamber, then the plunger 3 closes the opening in the follower 4, the jawsf9 finallyco-operatewith the follower 4 and move it down.

T Figures 3 and 4 illustrate a modified construc- 30 can of the apparatus according to the present invention. In' this construction also the rod 2 1 withthe plunger 3" at its bottom'fend is t ey able upia'nd down in the tube 1. Ho euer, in this construction the plunger 3"isofcylindrical shape,'guided by ribs 10 (for instance three ribs, Fig: 4) of the follower 4. Theconnecti'ng memar 5' bet-Ween the follower 4' and the ro 2? V is in the form'of ire ropes or chains which, as illustrated," extend up to the'head of the 99 irodj ifIhe jaws 19 are arranged on the follower l". During its downward movement the plunger 3" co-op'erateswith and moves down the fol lower,4'.'

When the apparatus is to be used for the pro- .du'ctjionof reinforced concretep'iles, the outer diametenof the follower is smaller than the inner diameter of the tube. The free annular sijac'e around the plunger must be large enough to the readyarrangementof the reinforcing 100 cagelz' so that it W ll not obstruct the up and r down moyement of the follower (Fig.

' 'The procedure for filling concrete into the top space 7 abo e the lifted plunger 3' and follower fl" isthe" same as descriloed'with 'referenceto ti l g' t 53 9 1 .110

The tube 1' is sunk to the depth required (Figure in any convenient manner, for instance by driving, the blows being applied in known manner directly to the rod 2 and the pile shoe 5 remaining permanently in the ground in order to spare the tubing 1.

Now concrete is filled into the tube 1 (Figure 6) and the rod 2' lifted slightly. Whenever a sufficient quantity of concrete is present in the tube 1, the rod 2 is rapidly lifted for some distance (Figure '7), whereby the follower 4' is lifted for some distance with theplunger 3. Now the concrete drops from the top space '7' of the tube 1' and through the bore 6 of the follower l into the bottom space 8' of the tubing. Hereafter the rod 2 is driven down (Figure 8) until the concrete underneath the plungers has been compressed to the desired density (Figure 9). In View of the continuous blows applied to the rods the concrete is forced out laterally of the tube whereby the latter is forced upward and a concrete enlargement 11 is formed at the base of the column (Figure 10).

The pile is gradually erected (Figure 11) by repeating this procedure, whereby the tube is stepwise pulled out. In Figure 11 the tube 1 is entirely pulled out and the follower 4' is freely suspended so that it is readily accessible for inspection and cleaning.

The plunger and follower arrangement described above renders it feasible to conduct concrete into the compression chamber 8 through the passage between the plunger 3' and follower l by lifting the rod 2' and thus to get the conerete below the tamping surface of the follower 4 without extracting the rod entirely from the tube. Notwithstanding, when letting down the rod, the plunger 3 and follower l form an uninterrupted tamping surface covering the entire cross sectional area of the tube, allowing the concrete to be pressed equally all over this area. Thereby the production of compressed concrete piles is considerably simplified compared with the use of an implement with a tamping rod of a diameter equal to the inner width of the sinking tube, which has to be entirely extracted from the tube when pouring in concrete and then lowered again into the tube for tamping the concrete.

The plunger and follower arrrangement described above possesses the further advantage that the height of the compression chamber can be chosen such as to allow of leaving, after each charge of filling material forced out from the tube during the concreting of a pile, a plug of compressed concrete Within the bottom end of the tube for the purpose of neutralizing any existing pressure of soil or sealing the tube against influx of artesian ground water. The height of this concrete plug can be adapted to the height of the actual soil pressure by actuating the filling and tamping work at a higher or lower level of the sinking tube.

This method alone makes possible the reliable production of concrete piles cast in situ, without permanent casing, on building sites where pressing soil or even artesian subsoil water is encountered.

Besides, obstructing the passage of the follower by concrete masses is entirely prevented. For when lifting the plunger 3 the entire filler column has to beaccelerated if it does not automatically and immediately pass into the bottom space or compression chamber of the tube through the opening 6 of the follower. The head imparted to the filler column by its acceleration, in addition to the frictional adherence of the filling material to the outer tube, results in the breaking up of all too cohesive filling materials and of obstructions, and consequently the filler is bound to fiow through the opening 6 of the follower. A blocking or obstruction is thus avoided even in the case of materials such as sand and stiff concrete.

A further advantage of the apparatus according to the invention, is that the rod 2 with the plunger 3 when descending substantially shuts the opening 6 of the follower 4. The effect of this is that, on one hand, a compression chamber is created underneath the follower 4, namely a space which is closed on top, and on the other hand, any formation of a bridge over the opening 6 and consequent obstruction of the latter, is prevented. In this manner filling material of any consistency, even fiuidity, may be placed under pressure and forced out of the bottom end of the guide tube without being able to escape upwards.-

In order that as much as possible of the clear width of the upper space of the tubing may be available for the filling material, the rod 2 is preferably made in known manner of bucklingresistant rolled section iron, for example a broadfia-nged I-iron which causes but a very small loss of space.

The improved effects of the apparatus described as compared with the means hitherto used consists not only in the greater economy in sinking as compared with other building in situ methods, but also in the circumstance that the sinking of shafts of relatively small diameter suflices since the columns can be widened, by pressing, to a greater diameter. This widening is possible in nearly every kind of ground, all that is necessary being to employ a greater mechanical energy for a longer period of time'when it is a question of overcoming the greater external resistances.

By way of further explanation it may be stated that in soft earths the Weight of the rod 2 alone with that of the hammer resting on it frequently sufiices for effecting one operation of the plunger to its full stroke. In this case the filling material which has passed into the pressure space 8 can without any diificulty produce a displacement of the earth by the amount of the plunger displacement and be extruded to a corresponding extent out of the pressure space. If the pressing operation be continued the resistance of the more and more compressed mass of material will naturally become greater and greater and it will then become necessary for producing complete compression strokes of the plunger to increase the plunger pressures by blows with a more or less heavy block or hammer.

It is obvious that in those cases where the deposited layers are formed in the first instance it will be necessary to expend from the start a greater pressing energy of the plunger. In all circumstances, however, by applying a suitable amount of mechanical work at any desired points it is possible to produce widening in the column.

What I claim and desire to secure by Letters Patent of the United States is:

1. In an apparatus for the formation of'columns in situ, the combination of a column-forming tube, with a plunger, an operative rod therefore movable in the tube, said plunger having a cross-area less than that of the tube to provide an annular passage therebetween, a follower in the tube below the plunger and provided with an axial passage, and means providing a loose connection between the plunger and the follower to limit the separation of the same to a predetermined interval when the plunger is raised in the tube.

2. An apparatus as claimed in claim 1 and comprising a tube having a smooth inner surface and uniform diameter and a rod having an I cross-section.

V 3. An apparatus as claimed in claim 1 and comprising a plunger having a lower surface of a 

